Historical revision is a valid practice whereby historians reinterpret the past from different viewpoints and in the light of new documents or research. Those who deny the Holocaust, however, call themselves revisionists in an attempt to gain scholarly legitimacy, trying to align themselves with the\u27 historians of the 1920s and 1930s who reinterpreted the causes of the first World War. Should libraries acquire materials that deny the Holocaust, whether through purchase or donation